109 lines
4.3 KiB
Plaintext
109 lines
4.3 KiB
Plaintext
//---------------------------------------------------------------------------//
|
|
// Copyright (c) 2013 Kyle Lutz <kyle.r.lutz@gmail.com>
|
|
//
|
|
// Distributed under the Boost Software License, Version 1.0
|
|
// See accompanying file LICENSE_1_0.txt or copy at
|
|
// http://www.boost.org/LICENSE_1_0.txt
|
|
//
|
|
// See http://boostorg.github.com/compute for more information.
|
|
//---------------------------------------------------------------------------//
|
|
|
|
#ifndef BOOST_COMPUTE_ALGORITHM_DETAIL_FIND_EXTREMA_WITH_ATOMICS_HPP
|
|
#define BOOST_COMPUTE_ALGORITHM_DETAIL_FIND_EXTREMA_WITH_ATOMICS_HPP
|
|
|
|
#include <boost/compute/types.hpp>
|
|
#include <boost/compute/command_queue.hpp>
|
|
#include <boost/compute/container/detail/scalar.hpp>
|
|
#include <boost/compute/functional/atomic.hpp>
|
|
#include <boost/compute/detail/meta_kernel.hpp>
|
|
#include <boost/compute/detail/iterator_range_size.hpp>
|
|
|
|
namespace boost {
|
|
namespace compute {
|
|
namespace detail {
|
|
|
|
template<class InputIterator, class Compare>
|
|
inline InputIterator find_extrema_with_atomics(InputIterator first,
|
|
InputIterator last,
|
|
Compare compare,
|
|
const bool find_minimum,
|
|
command_queue &queue)
|
|
{
|
|
typedef typename std::iterator_traits<InputIterator>::value_type value_type;
|
|
typedef typename std::iterator_traits<InputIterator>::difference_type difference_type;
|
|
|
|
const context &context = queue.get_context();
|
|
|
|
meta_kernel k("find_extrema");
|
|
atomic_cmpxchg<uint_> atomic_cmpxchg_uint;
|
|
|
|
k <<
|
|
"const uint gid = get_global_id(0);\n" <<
|
|
"uint old_index = *index;\n" <<
|
|
|
|
k.decl<value_type>("old") <<
|
|
" = " << first[k.var<uint_>("old_index")] << ";\n" <<
|
|
k.decl<value_type>("new") <<
|
|
" = " << first[k.var<uint_>("gid")] << ";\n" <<
|
|
|
|
k.decl<bool>("compare_result") << ";\n" <<
|
|
"#ifdef BOOST_COMPUTE_FIND_MAXIMUM\n" <<
|
|
"while(" <<
|
|
"(compare_result = " << compare(k.var<value_type>("old"),
|
|
k.var<value_type>("new")) << ")" <<
|
|
" || (!(compare_result" <<
|
|
" || " << compare(k.var<value_type>("new"),
|
|
k.var<value_type>("old")) << ") "
|
|
"&& gid < old_index)){\n" <<
|
|
"#else\n" <<
|
|
// while condition explained for minimum case with less (<)
|
|
// as comparison function:
|
|
// while(new_value < old_value
|
|
// OR (new_value == old_value AND new_index < old_index))
|
|
"while(" <<
|
|
"(compare_result = " << compare(k.var<value_type>("new"),
|
|
k.var<value_type>("old")) << ")" <<
|
|
" || (!(compare_result" <<
|
|
" || " << compare(k.var<value_type>("old"),
|
|
k.var<value_type>("new")) << ") "
|
|
"&& gid < old_index)){\n" <<
|
|
"#endif\n" <<
|
|
|
|
" if(" << atomic_cmpxchg_uint(k.var<uint_ *>("index"),
|
|
k.var<uint_>("old_index"),
|
|
k.var<uint_>("gid")) << " == old_index)\n" <<
|
|
" break;\n" <<
|
|
" else\n" <<
|
|
" old_index = *index;\n" <<
|
|
"old = " << first[k.var<uint_>("old_index")] << ";\n" <<
|
|
"}\n";
|
|
|
|
size_t index_arg_index = k.add_arg<uint_ *>(memory_object::global_memory, "index");
|
|
|
|
std::string options;
|
|
if(!find_minimum){
|
|
options = "-DBOOST_COMPUTE_FIND_MAXIMUM";
|
|
}
|
|
kernel kernel = k.compile(context, options);
|
|
|
|
// setup index buffer
|
|
scalar<uint_> index(context);
|
|
kernel.set_arg(index_arg_index, index.get_buffer());
|
|
|
|
// initialize index
|
|
index.write(0, queue);
|
|
|
|
// run kernel
|
|
size_t count = iterator_range_size(first, last);
|
|
queue.enqueue_1d_range_kernel(kernel, 0, count, 0);
|
|
|
|
// read index and return iterator
|
|
return first + static_cast<difference_type>(index.read(queue));
|
|
}
|
|
|
|
} // end detail namespace
|
|
} // end compute namespace
|
|
} // end boost namespace
|
|
|
|
#endif // BOOST_COMPUTE_ALGORITHM_DETAIL_FIND_EXTREMA_WITH_ATOMICS_HPP
|